Hermetically sealed lever operated switch



June 30, 1953 w. DIETRICH 2,644,061

HERMETICALLY SEALED LEVER OPERATED SWITCH med Nov. so, 195o 2 sheets-sheet 1 I nn/lzfo'rc. 'Wal/611 Dietrich 222/ Tris/9 wigs;

Patented June 30, 1953 HERMETICALLY SEALED LEVER OPERATED SWITCH Walter L. Dietrich, Hartford, Conn., assignor to The Arrow-Hart & Hegeman Electric Company, Hartford, Conn., a corporation of Connecticut Application November 30, 1950, Serial N o. 198,445

Claims.

This invention relates to electric switches.

by a lever and are usually a toggle-type mechanism.

Many of this type of switch have been used in airplanes which at one moment may be at a Vhigh or tropical temperature and only a short time later may be in extremely cold upper rarined atmosphere. Although such switches have often been enclosed, the usual enclosure did not prevent condensation in the form oi moisture, frost or ice which greatly interfered with the operation oi the switch or prevent it entirely on occasions. Obviously any such interference can be extremely hazardous or dangerous to life and property in an airplane when accurate and proper operation at any moment may become critical. Equally obviously hermetic sealing of the operating mechanism oi switches for such uses presents many advantages. The sealing of the mechanisrn prevents any arcing between the switch ccntacts from igniting gases and also prevents condensation from aiiecting the operation of contacts.

Therefore it is an object of my invention to provide a lever operated switch mechanism which will be positive in operation and may be hermetically sealed in such a way as to not interfere with the normal operation of the switch.

Another object or my invention is to provide a switch of the foregoing type wherein the sealing means avoids the use of rubber or other materials which are strongly ailected by moisture or changes in atmospheric conditions.

Another object of thenvention is to provide a switch oi the foregoing type which may be made economically, mainly from stamped sheet metal parts and may be assembled with a minimum labor expense.

Another object is to provide a switch having the foregoing characteristics which will be sturdy and reliable in operation over long periods of time and under various and severe conditions of use.

Other objects and advantages in the invention will become apparent as it is described in connection with the accompanying drawing.

In the drawing:

Fig. l is an end elevation View, partly in section. n

Fig. 2 is a Side elevational section view taken along line 2-2 of Fig. l.

Fig. 3 is a transverse section View of the invention of Figs. l and 2 along line 3--3 of Fig. l.

Fig. 4 is a transverse section view taken along line 4--4 of Fig. 2.

'More particularly it relates to switches which are Y 'operated from the exterior of a panel or casing Fig. 5 is a perspective view of the contact actuating lever and its supporting brackets.

Fig. 6 is a perspective View of one bridging contact element.

Referring to the drawing, the switch may conveniently be mounted on a plate l@ stamped in rectangular or other form from sheet metal and provided with a hollow semi-Spherical boss l2 in its middle cooperating with a similar semispherical boss ifi in the middle of the top surface of a shell or top enclosure member l. The shell may conveniently be stamped from sheet metal in inverted, hollow, oval, cup-shaped form. The top outer-surface of the shell I8 may be secured against the mounting plate lo in any suitable manner so that the bosses I 2 and I4 form a socket for the spherical mid-portion of an operating lever il@ having a handle operation 22 outside the shell and above the mounting plate IS. By manipulation of the handle t, the switch may be operated as will hereinafter more fully appear.

The lower or inner end of the operating lever it has parallel bifurcations 213 with nat sides between which is mounted one end of a contact actuating lever 2t. A pivot pin 23 passing transversely through the bifurcation and said end of the actuating lever affords a pivotal driving connection between those parts. The contact actuating member 26 whose details will be more particularly set forth may be stamped from sheet metal into the form illustrated best in Figs. 1 and 2. The contact actuating member 28 is pivotally mounted near its mid-portion on a iixed pivot pin Sil which is supported in lever-supporting members Si? and 3i in the form oi stamped sheet metal angle brackets. In order to permit movement of the drive pin 2B longitudinally of the contact actuating member 2t as the operating lever 2li is oscillated to move the actuating lever 25, the end of the lever 2S is slotted or biiurcated to receive the pin 2t (see Fig. 2).

The bracket 32 has a vertical leg 32e (referring to Fig. l) extending at right angles from a horizental substantially flat bar portion 32h. The bracket 34 has a vertical leg Sta parallel to the leg 32u extending at right angles to a horizontal mounting portion 315111. AS shown in Fig. l, the leg teta has a right-angled bend 3de in its connection to the horizontal mounting portion 34h. The mounting portion 34h is of substantially U-shape and has the end portions of the U offset and on these offset portions and across the U the horizontal mounting portion 32h of the other bracket is located as seen in Fig. 5. Registering apertures are provided in the offset portions Bild and 32h to receive securing means l such as a rivet 33 by means of which the brackets are secured together with their upper surfaces in the same plane.

The described construction of the brackets enables them to be secured against the inside of the top wall of a bottoni casing member 42. The casing member 42 may be stamped from sheet metal into hollow, oval form and affords a housing for the iixed and movable contacts of the switch. In order 'to permit the desired movement of the contact actuating member 2in, an opening 4i is formed in the top surface 4t of the casing member.

rIhe fixed contacts are mounted u'pon a `flat, oval-shaped insulating plate 44 of any suitable material. When a plate that Will not bei affected by moisture or the heat of soldering adjacent parts is required, i'lber glass is desirable and may be used. The fixed contacts may be of any desired number but for the purpose of illustration, l have shown three. These contacts may be stamped from sheet copper, brass or other suitable conductive metal to provide anchor portions or feet 45 lying upon the upper surface of the insulating plate 44 and having apertures stamped therein to register with similar' apertures in the insulating pla-te 44 in spaced positions. Hollow eyelets or rivets 48 may secure the fixed contacts to the insulating plate 44. Each of the fixed con-- tacts has an upstanding contact portion such as 5l, 52, 53 at right angles to the feet 46 and in a single plane in position to be engaged by the arms of a bridging contact member 54, as the switch is operated to its closed positions, or to bei disengaged when the switch is in open position as illustrated in Fig. 2.

The bridging contact member may comprise two identical leaves stamped from thin resilient highly conductive sheet meta-l into substantially U shape. These leaves are mounted respectively against the outsidcs of each of two parallel arc quenching plates 5G of insulating material. These arc quenching plates are secured against opposite sides of the end of the contact actuating llever 26 and are thus spaced apart. They are so located Ithat the fixed contacts 5I, 52 yand 53 enter into the space between the lower curved arcuate edges of the arc quenching plates. The arc plates and the movable contacts are secured upon the end of the contact actuating lever 2B t by a rivet which may be insulated from the end oi that lever by an insulating washer or other suitable means 62. Spaced notches are formed in the arcuate edges of the insulating plates. The notches in one plate being in register with the notches i the other in order that offset end portions of the movable contacts may enter and thus may engage the fixed contacts as actnuating` lever 26 pivots about its pivot 30 to cause movement of the other movable contact assembly.

In order to herinetically seal the top wall 4D of the casing 42 and at the same time permit movement of the contact actuating member 2S, `a circular plate or disc is provided with a slot in the middle thereof thro-ugh which the upper end of the contact actuating member 25 extends. In orde-r to locato this disc 1D, laterally extending' shoulders or extensions 'l2 are provided from opposite side edges oi the contact actuating mem,- ber 26 between the pivot 3 and pm 28 as may be seen in Fig. 2. rIhe disc 10 is soldered tothe contact actuating membei1 25 to form a tight seal. soldered to the periphery oi the Wafer 10 is the top end of circular metallic bellows 'I4 Whose bottom end is soldered around the periphery of the opening 4| in the top of the casing 40". In this manner the top of the casing is hermetically sealed by the ilexible bellows 14 in a` manner which permits entire freedom of movement within the limits necessary for the contact actuating member 26.

Often there are limitations upon the over-al1 depth of the switch and the amount of angular movement that the operating lever 20 may have. In order to provide the required degree of movement of the movable contact assembly under such conditions the relative locations of the stationary pivot '30 and the drive pin 28 are fixed andldetermined lby said conditions. In order that the bellows have adequate and maximum life, it is desirable that it have as many folds as possible and move a minimum amo-unt. Thus, if its top 10 be located near the fixed pivot, there must be greater initial compression of the bellows or the number of folds must be less; and the angular movement of the top will causey greater compressive and expansive flexing than ii' the top is farther from pivot 3l). When the top is' located asl far as possible from pivot 3U toward drive pin 28, the angle of tilt of the top will be lessened and hence there will be less compressive and expansive flexing of the bellows and at the same time the bellows may have a maximum number of folds.

In order to hermetically seal the bottom of the casing 42, a metallic bottom plate .'6 is stamped from sheet metal in form to conform to the lower interior Wall of the casing 42; and its periphery is soldered to that wall. In order to provide an exterior connection for the iixed contacts, three such as 78, are soldered at one end to the eyelets which secure the fixed contacts upon their insulating mounting plate 44. These rods extend through relatively large openings formed in the bottom casing plate 16. Each of these openings has a circula.r-fiange 'H extending outwardly around it in which a glass bead or bushing 19 is fused to the rod ill as well as to the walls of the flange l?. Preferably the rod 'IB will be of sufiicient to form` adequate Velectrical conductivity and will be of a material having coeflicient ci expansion approximately equal to that of the glass so that expansion and contraction of the rod will not cause cracking of the glass. Thus a hermetically sealed exterior connection for the fixed contacts is provided via the rods 18; and since `the bottom casing plate 16 is soldered tothe lower portion of the casing 42, the whole lower end of the casing is hermetically sealed.

If desired, a base'80 of molded insulating material can be provided through which the ends of the rods 18 may extend and be connected in conventional fashion to terminal plates such as 82 provided with conventional binding screws B4.

In order to hold the switch in its on and off positions, an indexi g leaf spring with a central opening for the bifurcations 24 on the operating lever 2U may be provided. The ends of the leaf spring may be secured to posts B8 extending into the top casing or shell It on opposite sides thereof. These posts may have reduced ends extending through the mounting plate l0 and top wall or shell i6 and be peened over to secure those parts together. The central portion of the leaf springs may -be formed with transverse semi-cylindrical grooves to afford a seat for the ends of the driving pin 28.

These ends extend beyond the bifurcations 24 of the operating member in which the pin is mounted. As the operating lever 253 is moved from the mid-position of 2 to the right or to the left, the driving pin 2S will move out from seat 8l and up on to the iiat top surface oi the springs Se thus biasing the upper lever lil into its new position. In this manner the operating lever may be held in any of its three positions.

in order that the air within the hermetically sealed casing may be evacuated and replaced with nitrogen or other inert gases, preferably without moisture content, an evacuating tube of metal Sil may extend through the hollow rivet 3S which secures the brackets 32, ed and top wall de Yci the casing @l2 together. The connecn tion between the evacuating tube te and the rivet and the casing wall may be soldered to form a tight seal. After the evacuation and nlling of the casing with the desired gas the evacu ating tube 9d will be sealed ofi at its top end as illustrated in Fig. l.

From the foregoing, it may be observed that i have provided a lever operated switch of a ice and forni permitting its use in ordinary spaces and locations where heretofore lever op=l erated switches have been employed; but at the same time I have provided for hermetically seal-1 ing of the switch contacts and actuating mechanism within a casing to isolate them fromvariN ations and atmospheric conditions. Also the invention provides for positive operation or the contacts under all conditions to overcome vany tendency of the contacts to sticir or resist movement from one position to another.

Many modifications within the scope ci the invention will occur to those skilled in the art. Therefore l do not limit the invention to the exact form and detail as illustrated and described.

What is claimed is:

l. An electric switch comprising and movable contacts, a contact-moving member for operating said contacts between engaged and dis-= engaged positions, an hermetically sealed enclon sure for said contacts including a rigid housing and flexible means sealed thereto, said flexible .means also being sealed to said contact-moving member with said member extending therethrough for manipulation outside the enclosure, said rigid housing part being laterally extended from its connection with said flexible means providing room for said contacts, and a pivot with- 6v in said enclosure for said contact moving memm ber, a tiltable operating member engaging the exteriorlf,7 extending portion ci said contact moving member, and means mounted on said enclosure to support said operating member exteriorly 0i said enclosure.

2. An electric switch as claimed in claim l having connecting means for said fixed contacts extending through the wall or" said enclosure, and a glass bead fused to said connecting means and to said enclosure.

3. An electric switch comprising fixed and movable contacts, rigid enclosing means for said contacts having an opening therein, a contactm moving member extending into said opening vfor operating said contacts betr eenY engaged and disengaged positions, lexible means around and sealed to said contact-moving member and through which said member extends for manipulation outside the enclosure, said flexible means also being sealed to said enclosing means to hermetically enclose said contacts, supporting means secured within said enclosure, and a pvot for said contact-moving member on said sup porting means within the area of said iiexible means.

An electric switch as claimed in claim 3 wherein the ilexible means is a metallic bellows and the connection of said bellows to said cons tact moving member is on the opposite side of said pivot from said enclosure.

An electric switch as claimed in claim 3 wherein the flexible means is a metallic bellows, a tiltable operating lever cooperating with the end or" said contact-moving member outside the bellows to move that member, said bellows being sealed to said contact-moving member more approximately to the point or" engagement of said operating member and said contact-moving member than to the pivot of said Contact moving member to provide minimum bellows movement.

lll/'ALTER L. DIETRICH.

References ones in vthe me or this patent UNITED STATES PATENTS Number Name Date 1,829,037 Bobroi Oct. 27, 1931 1,91e,717 Degiers July 4,1933 2,171,267 Doty Aug. 29, 1939 2,527,475 Bates Oct. 24, 1950 

